1. Field of the Invention
The present invention relates to systems for providing a telephone interface to a television system. More particularly, though not exclusively, the present invention relates to an apparatus and method for providing a transparent remote connection to a telephone/audio modem located on a coaxial cable distribution system.
2. Problems in the Art
Various systems exist in the prior art for providing television signals to a TV including off air antennas, direct broadcast satellites (DBS), conventional cable services, or MMDS (Multi-channel Multi Point Distribution System) systems. U.S. Pat. No. 5,394,559 issued Feb. 28, 1995, entitled MMDS/ITFS Bi-Directional Over the Air Transmission System and Method Therefore, which is assigned to the assignee of the present invention, describes an example of such a system and is incorporated by reference herein.
With any of these systems, there is a need to provide feedback from the consumer to the program delivery source. This feedback is typically used for pay per view services, but could also include purchasing information, computer data, etc. A typical prior art system for providing feedback from a consumer to the program delivery source includes the use of a set-top box which provides for a standard telephone line hookup for sending data back to the billing computer. This system can easily be installed by a customer to access pay per view programming, for example. However, many homes have multiple televisions which require multiple set-top boxes with a phone line connection at each set-top box. Connecting a telephone line to every set-top box is costly since a separate phone jack is required at each set-top box. FIG. 1 is a block diagram of such a prior art set up. As shown, a multi-set splitter is used to provide signals to a plurality of set-top boxes. Each set-top box is connected to a television. Each set-top box is also connected to a separate telephone jack (designated as "TELCO").
A prior art system exists for providing a telephone line connection to a plurality of extension phones without having a standard telephone jack located at each extension phone. This prior art system uses a device which communicates over the AC power wires found in a home. U.S. Pat. No. 4,495,386 issued on Jan. 22, 1985 entitled Telephone Extension System Utilizing Power Line Carrier Signals describes such a prior art system, and is incorporated by reference herein. FIG. 2 is a block diagram of a system using the AC power wiring to provide telephone line connections to a plurality of extension phones. As shown, a master linking circuit is connected to a standard power outlet which is connected to the AC power wiring of the home. The master linking circuit is also connected to a standard telephone jack. Elsewhere in the home, extension phones can be connected to extension linking circuits which are connected to other standard power outlets. The linking circuits use the AC power wiring to transmit and receive phone signals between the extension phones and the telephone jack. As is described in the above referenced patent, the interface devices allow telephone signals to be transmitted from the phone jack to each extension phone. A system which uses AC wiring to transmit phone signals has various disadvantages. For example, the equipment required for such a system is costly. Also, the 100 KHz and 200 kHz signals used for such prior art devices are susceptible to interference. Sources of interference include: microwave ovens, motors, remote control lighting, power line intercom systems, and remote speakers. In addition some 220 VAC services have a problem with AC power line signaling between the two legs of the 220 VAC power. The AC power wiring is not conducive to the radio frequencies due to lack of shielding from ingress and prevention of egress and the inability of the power wiring to pass the RF signals.
It can therefore be seen that there is a need for a system which provides a telephone line connection to a number of set-top boxes without the need of multiple telephone line jacks and without using AC wiring.